Hyperbilirubinemia has been a concern to Neonatologists and Pediatricians alike. In the United States women who have had a normal spontaeous delivery will be discharged with their newborn 36 to 48 hours after birth. Usually the jaundice doesn't become obvious to the parents until day four of baby's life and an inexperienced mother might even miss the first symptoms of hyperbilirubinemia. The vicious cycle of a sleepy jaundiced child who doesn't wake up for its feeds and therefore gets even more jaundiced due to lack of fluid intake takes its course. It would be very beneficial to know whether a newborn will get jaundiced to the degree that it requires phototherapy before the baby gets discharged from the hospital. This would spare the parents a lot of distress (readmission of child for phototherapy), give the pediatrician another tool to decide when to bring the baby back for follow-up and would save our health system a lot of money. The breath analyzer used in this study takes advantage of the carbon monoxide production in the infant's breath at 24 to 36 hours of life. As the CO in the endtidal breath (ETCO) is realted to the child's hemoglobin breakdown, it can estimate the subsequent bilirubin production. The baby's exhaled air is analyzed by a CO-Stat End Tidal Breath Analyzer and requires passive breathing for only 1 1/2 minutes. A special sampler is placed at the nostril of the baby to analyze the breath. To make sure that the child wasn't jaundiced at the time of the test (remember it is supposed to predict hyperbilirubinemia and not state the child's jaundice) a serum total bilirubin is measured at 24 to 36 hours postdelivery with the newborn screening test. At 96 hours (4th day of life) another bilirubin is drawn to relate the ETCO result to the child's jaundice. If the results fall below the 45th percentile or above the 95th of a standard hour bilirubin nomogram, the child exits the study. Otherwise the baby is monitored over the next 24 to 48 hours regarding its jaundice and if needed, placed under phototherapy. The ETCO result will ultimately identify neonates who are at high risk of developing hyperbilirubinemia and make painful blood sampling for a serum total bilirubin obsolete in the future. The goal is to establish a routine newborn screening test applied to all well babies in the nursery before discharge.